Convert command queue to a command list.

Quik.OpenTK/OpenTKPort.cs

@@ -65,7 +65,7 @@ namespace Quik.OpenTK
             _window.Focus();
         }
 
-        public void Paint(CommandQueue queue)
+        public void Paint(CommandList queue)
         {
             QRectangle view = new QRectangle(Size, new QVec2(0, 0));
 

Quik/CommandMachine/CommandEngine.cs

@@ -34,10 +34,12 @@ namespace Quik.CommandMachine
             return id;
         }
 
-        public void ProcessCommands(QRectangle bounds, CommandQueue queue)
+        public void ProcessCommands(QRectangle bounds, CommandList queue)
         {
-            if (!queue.Peek().IsCommand)
+            CommandEnumerator iterator = queue.GetEnumerator();
-                throw new ArgumentException("The first element in the queue must be a command frame.");
+
+            if (!iterator.Peek().IsCommand)
+                throw new ArgumentException("The first element in the iterator must be a command frame.");
 
             Reset();
 
@@ -45,7 +47,7 @@ namespace Quik.CommandMachine
             _viewportStack.Push(_viewport);
 
             Frame frame;
-            while (queue.TryDequeue(out frame))
+            while (iterator.TryDequeue(out frame))
             {
                 Command cmd = (Command)frame;
                 switch (cmd)
@@ -53,28 +55,28 @@ namespace Quik.CommandMachine
                 default:
                     if (cmd > Command.CustomCommandBase)
                     {
-                        _customCommands[cmd - Command.CustomCommandBase].Invoke(this, queue);
+                        _customCommands[cmd - Command.CustomCommandBase].Invoke(this, iterator);
                     }
                     else
                     {
-                        ChildProcessCommand(cmd, queue);
+                        ChildProcessCommand(cmd, iterator);
                     }
                     break;
 
-                case Command.ConditionalBegin:  ConditionalHandler(queue);       break;
+                case Command.ConditionalBegin:  ConditionalHandler(iterator);    break;
                 case Command.ConditionalEnd:    /* nop */                        break;
 
                 case Command.Invoke:
-                    queue.Dequeue().As<QuikCommandHandler>().Invoke(this, queue);
+                    iterator.Dequeue().As<QuikCommandHandler>().Invoke(this, iterator);
                     break;
                 case Command.PushViewport:
                     _viewportStack.Push(_viewport);
                     break;
                 case Command.IntersectViewport:
-                    _viewport = QRectangle.Intersect((QRectangle)queue.Dequeue(), _viewport);
+                    _viewport = QRectangle.Intersect((QRectangle)iterator.Dequeue(), _viewport);
                     break;
                 case Command.StoreViewport:
-                    _viewport = (QRectangle)queue.Dequeue();
+                    _viewport = (QRectangle)iterator.Dequeue();
                     break;
                 case Command.PopViewport:
                     _viewport = _viewportStack.TryPop(out QRectangle viewport) ? viewport : bounds;
@@ -86,10 +88,10 @@ namespace Quik.CommandMachine
                     _zIndex++;
                     break;
                 case Command.AddZ:
-                    _zIndex += (int)queue.Dequeue();
+                    _zIndex += (int)iterator.Dequeue();
                     break;
                 case Command.StoreZ:
-                    _zIndex = (int)queue.Dequeue();
+                    _zIndex = (int)iterator.Dequeue();
                     break;
                 case Command.DecrementZ:
                     _zIndex--;
@@ -101,7 +103,7 @@ namespace Quik.CommandMachine
             }
         }
 
-        protected virtual void ChildProcessCommand(Command name, CommandQueue queue)
+        protected virtual void ChildProcessCommand(Command name, CommandEnumerator queue)
         {
         }
 
@@ -110,16 +112,16 @@ namespace Quik.CommandMachine
             _zIndex = 0;
             _zStack.Clear();
 
-            _viewport = new QRectangle(float.MaxValue, float.MaxValue, float.MinValue, float.MinValue);
+            _viewport = new QRectangle(float.MaxValue, float.MinValue, float.MinValue, float.MaxValue);
             _viewportStack.Clear();
 
             _matrixStack.Clear();
             _matrixStack.Push(QMat4.Identity);
         }
 
-        private void ConditionalHandler(CommandQueue queue)
+        private void ConditionalHandler(CommandEnumerator iterator)
         {
-            Frame frame = queue.Dequeue();
+            Frame frame = iterator.Dequeue();
 
             if (
                 frame.IsInteger && (int)frame != 0 ||
@@ -131,11 +133,11 @@ namespace Quik.CommandMachine
 
             // Skip this branch.
             int depth = 1;
-            while (queue.TryPeek(out frame))
+            while (iterator.TryPeek(out frame))
             {
                 if (!frame.IsCommand)
                 {
-                    queue.Dequeue();
+                    iterator.Dequeue();
                     continue;
                 }
 
@@ -149,13 +151,13 @@ namespace Quik.CommandMachine
                     // Decrement condional depth, exit if zero.
                     if (--depth == 0)
                     {
-                        queue.Dequeue();
+                        iterator.Dequeue();
                         return;
                     }
                     break;
                 }
 
-                queue.Dequeue();
+                iterator.Dequeue();
             }
         }
     }

Quik/CommandMachine/CommandHandler.cs

@@ -4,5 +4,5 @@ namespace Quik.CommandMachine
     /// A delegate for a QUIK command.
     /// </summary>
     /// <param name="stack">The current stack.</param>
-    public delegate void QuikCommandHandler(CommandEngine state, CommandQueue queue);
+    public delegate void QuikCommandHandler(CommandEngine state, CommandEnumerator queue);
 }

Quik/CommandMachine/CommandList.cs

@@ -1,10 +1,25 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection.Emit;
 
 namespace Quik.CommandMachine
 {
-    public class CommandQueue : Queue<Frame>
+    public class CommandList : IEnumerable<Frame>
     {
+        private readonly List<Frame> _frames = new List<Frame>();
+
+        public void Clear()
+        {
+            _frames.Clear();
+        }
+
+        protected void Enqueue(in Frame frame)
+        {
+            _frames.Add(frame);
+        }
+
         public void Invoke(QuikCommandHandler handler)
         {
             Enqueue(Command.Invoke);
@@ -243,5 +258,84 @@ namespace Quik.CommandMachine
                 Enqueue(uvs[i]);
             }
         }
+
+        public void Splice(CommandList queue)
+        {
+            foreach (Frame frame in queue)
+            {
+                Enqueue(frame);
+            }
+        }
+
+        public CommandEnumerator GetEnumerator() => new CommandEnumerator(_frames);
+        IEnumerator<Frame> IEnumerable<Frame>.GetEnumerator() => GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+    }
+
+    public class CommandEnumerator : IEnumerator<Frame>
+    {
+        private readonly IReadOnlyList<Frame> _frames;
+        private int _current;
+
+        public Frame Current => _frames[_current];
+
+        object IEnumerator.Current => Current;
+
+        public CommandEnumerator(IReadOnlyList<Frame> frames)
+        {
+            _current = -1;
+            _frames = frames;
+        }
+
+        public void Dispose()
+        {
+        }
+
+        public bool TryDequeue([NotNullWhen(true)] out Frame frame)
+        {
+            if (MoveNext())
+            {
+                frame = Current;
+                return true;
+            }
+            else
+            {
+                frame = default;
+                return false;
+            }
+        }
+
+        public Frame Dequeue() => TryDequeue(out Frame frame) ? frame : throw new Exception("No more frames left.");
+        
+        public bool TryPeek([NotNullWhen(true)] out Frame frame)
+        {
+            if (_current + 1 < _frames.Count)
+            {
+                frame = _frames[_current + 1];
+                return true;
+            }
+            else
+            {
+                frame = default;
+                return false;
+            }
+        }
+
+        public Frame Peek() => TryPeek(out Frame frame) ? frame : throw new Exception("No more frames left.");
+
+        public bool MoveNext()
+        {
+            if (_current + 1 < _frames.Count)
+            {
+                _current++;
+                return true;
+            }
+            return false;
+        }
+
+        public void Reset()
+        {
+            _current = -1;
+        }
     }
 }

Quik/Controls/UIBase.cs

@@ -44,20 +44,20 @@ namespace Quik.Controls
         {
         }
 
-        protected virtual void PaintBegin(CommandQueue cmd)
+        protected virtual void PaintBegin(CommandList cmd)
         {
             cmd.PushViewport();
             cmd.StoreViewport(AbsoluteBounds);
             cmd.PushZ();
         }
 
-        protected virtual void PaintEnd(CommandQueue cmd)
+        protected virtual void PaintEnd(CommandList cmd)
         {
             cmd.PopZ();
             cmd.PopViewport();
         }
 
-        public void Paint(CommandQueue cmd)
+        public void Paint(CommandList cmd)
         {
             PaintBegin(cmd);
             PaintEnd(cmd);

Quik/PAL/IQuikPort.cs

@@ -44,6 +44,6 @@ namespace Quik.PAL
         /// Paint the given command queue onto the port.
         /// </summary>
         /// <param name="queue">The command queue to paint.</param>
-        void Paint(CommandQueue queue);
+        void Paint(CommandList queue);
     }
 }

Quik/QuikApplication.cs

@@ -50,7 +50,7 @@ namespace Quik
         public void Run(View mainView)
         {
             IQuikPort port = Platform.CreatePort();
-            CommandQueue cmd = new CommandQueue();
+            CommandList cmd = new CommandList();
 
             MainView = mainView;
 
@@ -61,6 +61,7 @@ namespace Quik
                 Platform.ProcessEvents(false);
                 if (port.IsValid)
                 {
+                    cmd.Clear();
                     MainView.Paint(cmd);
                     port.Paint(cmd);
                 }

Quik/VertexGenerator/VertexCommandEngine.cs

@@ -30,7 +30,7 @@ namespace Quik.VertexGenerator
             DrawQueue.Clear();
         }
 
-        protected override void ChildProcessCommand(Command name, CommandQueue queue)
+        protected override void ChildProcessCommand(Command name, CommandEnumerator queue)
         {
             base.ChildProcessCommand(name, queue);
 
@@ -55,7 +55,7 @@ namespace Quik.VertexGenerator
         }
 
         private readonly List<QLine> LineList = new List<QLine>();
-        private void LineProc(CommandQueue queue)
+        private void LineProc(CommandEnumerator queue)
         {
             Frame frame = queue.Dequeue();
 
@@ -280,7 +280,7 @@ namespace Quik.VertexGenerator
         }
 
         private readonly List<QBezier> BezierList = new List<QBezier>();
-        private void BezierProc(CommandQueue queue)
+        private void BezierProc(CommandEnumerator queue)
         {
             Frame a = queue.Dequeue();
             Frame b;
@@ -397,7 +397,7 @@ namespace Quik.VertexGenerator
         }
 
         private readonly List<QRectangle> RectangleList = new List<QRectangle>();
-        private void RectangleProc(CommandQueue queue)
+        private void RectangleProc(CommandEnumerator queue)
         {
             Frame frame = queue.Dequeue();
             RectangleList.Clear();
@@ -422,8 +422,8 @@ namespace Quik.VertexGenerator
             {
                 QRectangle outer = RectangleList[i];
                 QRectangle inner = new QRectangle(
-                    outer.Right - stroke, outer.Top - stroke,
+                    outer.Right - stroke, outer.Bottom + stroke,
-                    outer.Left + stroke, outer.Bottom + stroke);
+                    outer.Left + stroke, outer.Top - stroke);
 
                 GenerateRectangleBase(inner, Math.Max(radius - stroke, 0.0f));